This idea comes from the founder of Missing Cats in Scotland and Missing Cat in England. She makes a very good point. Cat owners who lose their cats but cannot find them are unable to close the matter. There is uncertainty.
Often these cats will be killed on the road and sometimes they will crawl and stagger under a bush beside the road to die but sometimes they might be picked up by the local councils. It has to be said, by the way, that a lot of cat owners don't really seek closure and don't care that much when their cat fails to come home. But the majority do.
That said, it would not take much in the way of resources and effort for the local councils to ensure that their cleansing departments carried microchip scanners which could check whether the dead cat on the road was microchipped and if so identify the owner. They could then pass on the information.